NOTES. 



349 



According to Dulk ( "Chemische Untereucbung der Krebsteine :" MUUer's 

 Archiv. 1835), the gastroliths have the followiDg composition : — 

 Animal matter soluble In water .... 11'4.B 

 Animal matter insoluble in water (probably cliitin) 4-33 



Phosphate of lime 18'60 



Carbonate of lime 63']6 



Soda reckoned as carbonate 1'41 



98-93 



The proportion of mineral to animal matter and of phosphate to car- 

 bonate of lime is therefore greater in the gastroliths than in the exo- 

 skeleton in general. 



Note III., Chapteb I., p. 31. 

 GROWTH OF CKATFISH. 



The statements in the text, after the words " By the end of the year," 

 regarding the sizes of the crayfish at different ages, are given on the 

 authority of M. Carbonnier (L'^^crevisse. Paris, 1869) ; but they obviously 

 apply only to the large "Ecrevisse i, pieds rouges" of France, and not to 

 the English crayfish, which appears to be identical with the " Ecrevisse 

 A, pieds blancs," and is of much smaller size. According to M. Carbonnier 

 (1. c. p. 61), the young crayfish just born is " un centimetre et demi 

 environ," that is to say, three-fifths of an inch long. The young of the 

 English crayfish still attached to the mother, which I have seen, rarely 

 exceeds half this length, 



M. Soubeiran (" Sur I'histoire natnreUe et I'education des ificrevisses : " 

 Comptes Eendus, LX. 1865) gives the result of his stndy of the growth 

 of the crayfishes reared at Clairefontaine, near Eambouillet, in the 

 following table : 



These observations must also apply to the " Ecrevisse i, pieds rouges. 

 24 



